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Date: Tue, 16 Dec 1997 00:00:02 -0800 (PST)
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From: Bruce Evans <bde@zeta.org.au>
Subject: Re: bin/5306: gethostbyname() returns herror "Unknown host" on well known hosts
Reply-To: Bruce Evans <bde@zeta.org.au>
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The following reply was made to PR bin/5306; it has been noted by GNATS.

From: Bruce Evans <bde@zeta.org.au>
To: freebsd-gnats-submit@FreeBSD.ORG, robert@superior.net
Cc:  Subject: Re: bin/5306: gethostbyname() returns herror "Unknown host" on well known hosts
Date: Tue, 16 Dec 1997 18:49:02 +1100

 >>Description:
 >When on a well loaded system, gethostbyname() will return "Unknown
 >Host" on well known hosts. (ie: mit.edu, internic.net, etc.)  On a loaded
 >...
 >Not sure if this makes a difference, this kernel has:
 >options         "CHILD_MAX=256"
 >options         "OPEN_MAX=256"
 
 These are bogus, but misconfiguring the soft openfiles limit by abusing
 OPEN_MAX like this makes the problem less obvious.  The default limit
 is 64 in 2.2.5 and "infinite" in -current.
 
 >Load up a BSD system in which a lot of file discriptors are used. 
 >Compile and run something easy such as Squid and see that it's DNS
 >systems fail.  On this system named is running.  This is not that 
 >difficult to reproduce.
 >>Fix:
 >No fix as of 2.2.5-STABLE
 
 At least for the test program in PR 3622, the fix is to configure enough
 fd's using /etc/login.conf.  In 2.2.5, the default openfiles limits for
 class daemon are 1024 (hard) and OPEN_MAX (soft).  These should be set
 as large as necessary (but no larger) for each class of user.
 
 There is also an evil sysctl limit `kern.maxfilesperproc' with the
 default value of 2*NPROC.  This interferes with correct operation of
 login.conf.  If it is too small, then the easiest way to fix it is to
 edit /sys/conf/param.c and build a new kernel.  There is also a good
 sysctl limit `kern.maxfiles' with the default value of 2*NPROC.  This
 is easy to change at runtime using `sysctl -w kern.maxfiles=...'.
 (Changing kern.maxfilesperproc at runtime doesn't work well because
 it can't increase the openfiles limits in the process tree.  It can
 only decrease them.)
 
 Bruce